Preheat oven to 350°. Sift the dry ingredients together into a 10" cast iron skillet (also works well in an 8x8 baking pan). Make 3 wells in the dry ingredients. Pour vegetable oil in the first, vinegar in the second and the vanilla in the third well. Pour the cold water over the top. Stir with a fork until well blended. Bake for 25 minutes. Don't forget to use a hot pad when grabbing the handle!! Let cool then frost.